A series of very high-res photos of the Mona Lisa reveal 25 “secrets” such as its original colors, the reason for the positioning of her hand, and a trace of an eyebrow, a Parisian engineer says.

Among other things, he uncovered a bigger smile that might have been an abandoned draft of the portrait. Pascal Cotte spent 3,000 hours analyzing his photos, which included infrared and ultraviolet information “usually apparent only to insects,” according to InsideBayArea.com.

The photos are on display in a larger exhibit about Da Vinci until Dec. 31 at Metreon in San Francisco.

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